Method and apparatus for depositing tow



Feb. 14, 1961 J. T. BURNS 2,971,243

METHOD AND APPARATUS FOR DEPOSITING TOW Filed Feb. 3, 1960 2 Sheets-Sheet 1 +FIG.I

I'll

-l I a 6 y) INVENTOR JOHN T. BURNS ATTORNEY 2 Sheets-Sheet I2 l 2 INVENTOR JOHN T. B URNS ATTORNEY Feb. 14, 1961 J. T. BURNS METHOD AND APPARATUS FOR DEPOSITING TOW Filed Feb. 3, 1960 400 TOW UENIER y fi SURE (RS.|.G.)

SQUARE ROOT or STATIC GAS PRES 5 Sun; :3

FIG.4

United States Patent@ METHOD AND APPARATUS FOR DEPOSITING TQW John T. Burns, Ayden, N.C., assignor to E. I. du Pout de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Feb. 3, 1960, Ser. No. 6,545

2 Claims. (Cl. 23 -21 This invention relates to methods and apparatus for handling rapidly moving filamentary material, and. is concerned especially with the delivery of textile tow material inorderly arrangement.

Methods and apparatus have been previously described for depositing continuous filamentary material such as yarn on a s pport byblowing the yarn through a tube revolving about an axis passing through one end of the {tube .to deposit the yarn in the iorm of piled or overlapping loops ,or coils. However, when attempts were made to use these previously known procedures for handling Qtow, i.e., large bundles of substantially continuous filamerits, ,difliculty was encountered with the entanglement offilaments making up ,the tow bundle. Furthermore, when theprocedure was used as a method of collecting .undrawn synthetic fibers, it was discovered that during the subsequent drawing operation nonuniformly drawn sections ,were developed in the tow which led to non- ,uniform dyeing in fabrics prepared from the drawn fibers.

A primary object of the present invention is the provision of a method of controlling the delivery of a rapidly moving textile tow so that it is deposited upon a surface without the formation of looped or entangled filaments.

A further object is the provision of a controlled method .of depositing an undrawn synthetic fiber tow into areceptacle in a relaxed state in such a manner that the filaments of the tow bundle remain essentially parallel. These and other objects of this invention, together with means and methods of accomplishing the various objects, will be apparent from the following description and the accompanying drawings.

' The objects of this invention are accomplished, with large tows of 10,000 to 500,000 total denier travelling at high speeds of 500 to 2500 yards per minute, by feeding the tow in a downward direction to fluid jet forwarding means arranged to discharge the tow outwardly at an angle of 30 .to 75 to the original downward direction of feed while revolving about the feed to deposit the tow in a helical coil on a support, provided that the operation of the fluid jet is controlled within narrow limits which involve critical relationships between the denier of the tow, the speed at which the tow is fed, the area of the minimum cross section of the jet stream, the static pressure of the gas forming the jet stream and the flow of gas. It has been found that a surprising improvement in the {operation is accomplished by critical control of these variables and that the entanglement of filaments previously encountered when handling tows of synthetic fibers "athigli speeds can be substantially eliminated.

" In the drawings, which illustrate preferred embodiments V of the invention,

Figure l is a plan view partly in section showing a specific embodiment of an apparatus useful for carrying outihe invention,

" Figure 2is an enlargedview of apreferred embodiment of the'jet fotwyi dingrneans 5 of Figure 1,

Figure 3 is a graph "ill us'trating the preferred internal 2,071,243 Patented Feb. 14, 3961 ice be obtained directly from a synthetic fiber spinning machine, is passed over forwarding pulley 2 and then in a downwardly direction into confining tube 3. The tow then passes around pulley 4, making an angle between about 30 and with the initial downward path of travel, and is then passed through jet forwarding means 5. Air or other inert compressed gaseous fluid is passed into pressure tube 6 through throttling valve 7, to provide the desired pressure as indicated on gage 8, and enters the rotating part of the apparatus through sliding hollow collar 9. The compressed gaseous fluid is then passed through gas tube 10 into jet forwarding means 5 where it is brought into contact with the tow bundle. The whole assembly of parts 3, 4, 5, and 10 is rotated about an axis through the center of vertical tube 3 by means of a pulley, not shown to discharge the tow in the form of a helical coil in collection drum l1.

Figure 2 shows the construction of a preferred jet forwarding means; The tow bundle enters the jet through inlet tube 12 projecting into foretube 13. The tow passes from the inlettube into the foretube and through throat 14 which is the point of minimum diameter of the foretube. Compressed gaseous fluid is supplied through gas tube 10 to plenum chamber 15 from Where the gas is discharged into the foretube through annular opening 16 formed between the outside of inlet tube .12 and the inside of the inlet end of theforetube. The chamber surrounds the inlet tube and the end of the foretube, With thread engagement being provided with the inlet tube at 17 and the foretube at 18, so that the relative positions of the tubes can be adjusted to vary the size of the annular opening 16. The tow passes through the inlet tube, which should be of suitable size to accommodate the tow without excessive back-flow of gas, and into the foretube to be pulled along bythe forwarding action of the jet formed by the gas discharging through the throat. In order to provide for an efficient flow of gas, the foretube tapers outward gradually from the throat in the direction of tow travel at a divergence angle 19, which is suitably from 15 minutes to 3, and may also flare outward towaigs the inlet end at an angle 20 which may be up .to

It has been found that there is a critical relationship between the cross-sectional area of the throat 14 and the denier of tow which can be handled without entangling of filaments. For example, a jet having a throat diameter of 0.500 inch or cross-sectional area of 0.196

equare inch is suitable for handling tow of 125,000 to 300,000 total denier, measured in grams per 9000 meters, travelling at speeds of 500 to 2500 yards per minute when the static pressure of the gas and the flow of gas through annular orifice 16 are critically adjusted as disclosed hereinafter. This jet forwarding means may suitably have an internal inlet tube diameter of about 0.420 and a foretube length, measured from the end of the inlet tube at 21 of 14 to 22 times the throat diameter. The angle of divergence 19 in the tow direction is suitably 15 minutes to 3 and that of the angle 20 in the other direction from the throat, 0 to 10. Taking this jet forwarding meansas a basis for comparison, the relationship between tow denier and satisfactory throat crosssectional areas is shown in Figure 3. In this grapha jet index number of 1:1.0 means that the cross-sectional 3 area of the throat is 0.196 square inch and 1:08 indicates an area of (0.8)(0.196)=0.157 square inch. The graph indicates that, for any given denier of tow, the cross-sectional area of the throat must be within the range of J =0.00222 /50.22 and where D is the tow denier in grams per 9000 meters. In general, the jet stream must have a minimum cross-sectional area (A) in square inches, i.e., at the throat, which is numerically equal to a value within the range defined by 0.000435 /D0.043 and 0.000760 /D-0.072 where D is the total denier of the tow to be conveyed.

The size of the annular opening 16 must be adjusted within critical limits to give the proper flow of gas for the particular cross-sectional area of jet throat. Therefore, this adjustment is also interrelated with the denier of tow to be conveyed. Since actual measurement of the internal clearances is difficult, it is more convenient to determine the setting which will provide a specified flow in standard cubic feet per minute (s.c.f.m.) when tested with air supplied at a static pressure of 60 pounds per square inch gage (p.s.i.g.) without tow in the jet. Proper adjustment under these conditions is a setting that will pass an amount of air in s.c.f.m. which is numerically equal to (1601-28) /A where A is the crosssectional area of the throat in square inches.

If it is desired to use a gas pressure other than 60 p.s.i.g. for the adjustment of the internal clearance of annular opening 16, the correct gas flow is approximately equal to 160i 28) t Z( standard cubic feet per minute where P is the static pressure in p.s.i.g.

In actual operation the static gas pressure can be from 26 to 163 pounds per square inch gage, dependent upon the speed at which the tow is fed through the jet. The critical relationship between the static gas pressure and the tow speed is shown in Figure 4. The tow speed must excessive amount of filament entanglement and loop formation is observed. Since methods of controlling gas pressure are well known in the art, no specific method will be described here.

It is to be recognized that an important feature of the process of this invention is the placement of the jet forwarding means at the delivery end of the rotatably mounted apparatus. Attempts have been made to place the jet forwarding means in the vertical path of travel of the tow bundle, upstream from the outward turn made by the tow before it is discharged into the atmosphere, but operation in such manner always leads to an excessive amount of filament entanglement.

It is a requisite of this invention that both the internal dimensions of and the pressure of the fluid supplied to the jet forwarding means fall within the prescribed. limits. If either of these parameters fall outside of the limits described herein, the advantages of the invention are not obtained. a

The following examples further illustrate specific em. bodiments of this invention:

4 EXAMPLE 1 Apparatus for the delivery of tow is set up as shown in Figure 1. The jet forwarding means 5 has a jet index of 1.0, i.e., the intern-a1 diameter of the inlet tube 12 is 0.420 inch and the internal diameter of the foretube throat 14 is 0.500 inch. The internal angle 20 between the diverging foretube walls at the inlet is 8 and the angle 19 downstream of the throat is 130. The jet annular opening 16 is set to deliver 72.7 s.c.f.m. at 60 p.s.i.g. with no tow'in the jet. Compressed air is applied to the jet forwarding means at 35 p.s.i.g. The angle of the delivery tube is set at 47 from the vertical, and the shaft is rotated at about 225 r.p.m. The delivery tube is positioned about twelve inches above the top of a collection drum, which is sixty inches in diameter and sixty inches high. The drum is rotated at 3 r.p.m., the center of the drum being ofiset nine inches from the axis of rotation of the delivery apparatus.

Undrawn polyethylene terephthalate fiber tow approximating 195,000 denier (roughly 43,000 individual filaments) is fed to the apparatus at 830 yards per minute using conventional forwarding apparatus and guides, and deposited in the drum in overlapping loops. When the tow is subsequently withdrawn from the drum for further processing on a drawing apparatus, it is discovered that the number of draw machine stops due to entangled filaments is less than 0.10 stop per thousand pounds of tow processed. Furthermore, when the drawn tow is cut into staple, spun into yarn, woven into a fabric and dyed, the number of dyeing defects due to undrawn yarn sections is less than about 0.7 per square yard of fabric.

When the procedure of Example I is repeated using a jet forwarding means having a jet index number as defined in connection with Figure 3 of 1.5 and an air pressure of 60 p.s.i.g., it is found that the number of draw machine stops because of entangled filaments in the tow is about .35 stop per thousand pounds. Dyed fabric prepared from the tow exhibits an average of 3.5 defects per square yard.

I In like manner, when the procedure of this exampleis repeated using jet forwarding means having an index number of 0.60, and with air supplied at 40 p.s.i.g., an excessive number of entangled filaments is encountered with non-uniform delivery. Further, fabric prepared from the tow exhibits an excessive level of dyeing defects.

EXAMPLE II The procedure of Example I is repeated with the exception that the tow bundle has a total denier of 79,500, and is fed to the delivery apparatus at a rate of 1600 yards per minute. The jet forwarding means of the delivery apparatus has a jet index number of 0.5 and is supplied with air at 86 p.s.i.g. The jet annular opening has been set to deliver 46 s.c.f.m. at 60 p.s.i.g. Tow is delivered into a drum as previously described. The jet is rotated at the rate of 435 r.p.m.

When the tow is removed from the drum for drawing, it is found that the number of draw machine stops because of entangled filaments is less than 0.1 stop per one thousand pounds. Dyed fabric prepared from the tow exhibits a defect level of about 0.6 defect per square yard.

When the procedure of Example'II is repeated with a jet forwarding means having a jet index number of 1.0 and with air supplied at 55 p.s.i.g. (outside the critical limits as defined in this invention for the tow speed used) it is found that the number of draw machine stops due to entangled filaments is approximately 0.5 stop per thousand pounds. Processing of the tow into dyed fabric yields fabric having approximately 4.0 defects per square yard. 7

In like manner, when the procedure of this example is repeated with a jet forwarding means having an index number of 0.30 and with air supplied at 75 p.s.i.g., it is found that the system is not operable.

Theprocedure of Example I is repeatedwith the exception that the tow bundle has a total denier of 251,000 (approximately 12,000 filaments) and is fed to the de- 56 The vprefeigred fluid for the operation of jet forwarding means of Figure 1 is air, although'other gases maybe used with equal efiect. Minor amounts of reactive vapors may be included in the gas stream, if chemical livery apparatus at a rate of 789 yards per minute. The 5 x3 2: 3 3 2 122: z gig i g i ggs in the jet forwarding means 5 of the delivery apparatus has an g p examples have referred to the deposition of the tow mto Index number of which cpr'responds lto'lan Inlet tube a circular drum the invention ma also be used for dediameter e of 0.448 and a foretube throat .diameter of ositin the u on a flat surfgce or u n movino 0.536. Air is supplied to the jet forwarding means at a Eonve belt p P0 a pressure of 42 p.s.i.g. The tow is deposited in overlapping 10 many different embodiments of the invention y loops m a drum pmvlously described be made without departing from the spirit and scope when the tow is removed from the drum thereof it is to be understood that the invention is not it is found that the number of draw machine stops at- 1 I v limited by the specific lllustratlons except to the extent tnbutable to entangled filaments is less than about 0.1 r defined in the 011 owin claims stop per thousand pounds. When the tow is processed I Salim. g into staple fiber, spun into yarn, woven into a fabric, and dyed, it is found that the dye defect level is approxi- Z proiess f E ig deposlglng a ragldly mately 05 defect Per Square yard. miwmcg 02v 0 su stant1aby fcogtmuolps amentsdm a When the procedure of Example III is repeated with g s g z a 5 3 l g g f gs: a forwarding means having an index number of 0.75 o p g e wardly at an angle of 30 to 75 to said downward diand W1th a1r supplled at 55 p.s.1.g., 1t is found that the system is not Operable rectlon, conveymg the tow through sa1d passageway w1th Similarly, when the procedure of Example III is rea Slream ofgas and dischargn-lg the tow onto l support wh1le revolving the point of discharge about said downpeated w1th a et Iorwardmg means havlng an index numward d1rect1on of feed to deposlt the tow 1n a helical ber of 1.50 and air supplied at 60 p.s.1.g., an excessive coil on the Sn on the im rovement for de osifin a number of entangled filaments is encountered. pp p g pile of relaxed tow from whlch the tow can subsequently EXAMPLE IV be withdrawn without substantial entangling of filaments Following the general procedure of Example I, polyn which compnseinmiroducmg. i sald passageiway a let ethylene terephthalate tow is delivered under various com.- f of gas 32 Pfi i cr9ss'sectlonal area binations of conditions as described in Table I below. m P 9 me es w 1c 15 numerically Equal to a The number of draw machine stops attributable to en- Value Wlthln thifange defined y 0-000435VD 0-043 tangled filaments as well as the number of dyeing defects and 0.000760 /D. 0.072 where D is the total denier in fabric prepared from the drawn fiber, listed in the table, r of the tow to be conveyed, supplying the gas to form clearly indicate the criticality of the process conditions said jet stream under a static pressure of 26 to 163 defined in the appended cla1ms. pounds per square inch gage at a rate of flow in standard Table I Tow Air Pres- Jet Ro Fabric Run No. Tow, Speed, Jet sure, tation Entangle- Dye Denier y.p.m. Index p.s.i.g. Speed, merit Stops Detects r.p.m.

195, 000 830 0. 5 70 230 inoperable 195,000 830 0.75 230 0.4 5.0 105,000 830 1.0 40 250 0.08 0.08 0.7 0.7 195,000 830 1.5 230 0.35 0. 7.0 7.0 132, 000 1, 000 0. 4 so 420 inoperable 132,000 1.000 0.75 86 420 0.05 0.0 0.0 132,000 1,000 1.15 00 420 0. 50 3.2 132,000 1, 000 1.27 420 0.37 3.5 79,500 1, 000 1.27 55 435 0.55 4.5 as, 200 1, 000 0. 35 77 415 0.09

Although the process of this invention has been decubic feet per minute which, in the absence of tow, is scribed with particular reference to the handling of poly- 55 numerically equal to ethylene terephthalate tow, it is to be understood that the 13+ V advantages of the process accrue to the handling of other (1603: 28) /Z(- types of polyester tows as well as to tows prepared from 75 other synthetic polymers such as the polyamides, polywhere P is the static pressure of the gas and A is as dere the acrylics and t r y yp and to tows 6O fined above, and feeding tow of from 10,000 to 500,000 prepared frorn cellu1ose der1vat1ves. total denier into said passageway with the jet stream The present lnvenuon prov1des an improved method of at a speed 1n yards per minute which is numerlcally fleposltlilg d i i w fiberhtow th t tg t c011 equal to a value within the range defined by 313 1491 1n a re axe s a a 111 sue a manner a e ow can n be withdrawn from the pile without encountering an 223 313W 1097 where P 18 the Static pressure of the excessive number of entangled filaments. Furthermore, 2. In an apparatus for depositing a rapidly moving the filaments are maintained 1n substantlally parallel relatow in a helical coil on a support including means for tionship with each other across the tow bundle so that feeding the tow in a downward direction to a tow when tension subsequently applied to the tow bundle, positing tube directed outwardly at an angle of to i tenslon 1S dlsmbuted til/61113 aiming the filaments to said downward direction and means for revolving I-P t z f fl l ;d l 1; {gf: if xfig the gischarge egddof saiddtuibe aroundf afn :xis coreca ying on e me o 1 1nven1 n e 1 1 s a spon mg to sai ownwar irection 0 cc tow orgreatly reduced abras ve efiect upon the filaments of the warding means located at the entrance of said tube comtow being processed 1n comparison with other types of prising a jet tube having a minimum throat cross-sectional tow delivery apparatus, 75 area in square inches which is numerically equal to a amen . 7 value within the range given by 0.000435 /D -0.043 and 0.000760 /I j0.072 where D is the total denier of the tow and D is from 10,000 to 500,000 denier, said jet orifice tapering outwardly from said throat at an angle of from 15 minutes to 3 in the direction of tow travel and at an angle of 0 to 10 in the inlet end direction, a tow feeding tube projecting into the inlet end of said jet tube, a gas chamber surrounding said tow feeding tube and opening into the inlet end of said jet tube, means for supplying gas to said chamber at a pressure of 26 to 163 pounds per square inch gage, means for adjusting the flow of gas into said jet tube to (160:28) VZ standard cubic feet per minute, where A is said cross-sectional area of the throat and the flow is determined with air at'60 pounds per square inch gage pressure without tow in the jet tube, and means for feeding tow to said feeding tube at a speed in yards per minute which is numerically equal to a value within the range given by 313 /T 1491 and 313 /P-1097 where P is the pressure of gas in said gas chamber in pounds per square inch gage.

References Cited in the file of this patent UNITED STATES PATENTS 2,447,982 Koster Aug. 24, 1948 

